Next to HOUSE ON HAUNTED HILL, this is my favorite William Castle movie. Vincent Price is pathologist Warren Chapin, who has a theory that a creature grows in people when they experience fear. He calls this "The Tingler". He works out of the lab in his house while his rich, faithless wife runs around in front of his face. His lab assistant is engaged to his young sister-in-law, who he treats like a daughter. Neither of them like the wife much.

Warren's theories are proven correct when he threatens his wife and shoots her with a blank. She faints, but is terrified before he does so. He quickly puts her body on the x-ray table and is able to photograph the little monster. It's a dark, wormlike shape attached to the spine. He believes it starts off microscopic and rapidly grows when fear is unable to be expressed through a scream.

The main story is when Warren meets up with an old guy who runs a movie theater. The guy's wife is a deaf mute and has a phobia of blood. So when he accidently cuts himself she passes out, since she is unable to scream. She would be the ideal subject to scare and see if the Tingler appears. His wish soon comes true. After one of his visits she wakes up to find a guy in a horrible mask, holding a hatchet, after her. She runs into the bathroom where blood begins coming out of the faucets and the bathtub is filled. This is a very cool sequence because all of this blood is bright red, while the rest of the movie is in black and white. When a bloody hand emerges from the bathtub blood she dies of fright. Her husband brings her to Warren, since he says he doesn't know what else to do. But her body is moving....Warren does an autopsy and removes a two-foot long living Tingler from her body and puts it in a terrarium. It escapes and he must capture it before it kills someone else...

For most of the movie we're not certain if Warren was the one who scared the mans's wife to death in his quest for proving his theories correct. Yes, it is kind of a goofy movie but Vincent Price's performance manages to make it seem believable. If you're a horror fan this is a "must see" movie.